300 The Living Plant 



(the endosperm), devoted to nourishing the embryo in its growth. 

 At first sight it would appear as if the embryo and the endosperm 

 were brothers, so to speak, one of which later feeds eannibalis- 

 tically upon the other; but probably this is not its meaning. It is 

 more likely that the fusion is simply a method of providing a 

 stimulus for the formation of the endosperm; — a signal, so to 

 speak, to the waiting embryo sac nucleus that fertilization has 

 really been accomplished and therefore the endosperm will be 

 needed, — for the endosperm does not form unless fertilization is 

 accomplished. The matter, however, would have a purely 

 scientific interest were it not for a rather well-known phenomenon 

 it explains. Most people are aware that some varieties of corn 

 produce red ears while others have white ones, and that some- 

 times, where the two kinds grow together, red grains appear on 

 the white ears. This has long been known to be due in some way 

 to the influence of the pollen of the red kind upon the white ears, 

 but the remarkable matter about it was this, that the color was not 

 in the embryo, where its presence would be natural, but in a part 

 of the grain which was apparently made by the white parent. 

 Here was a case in which the male parent not only fertihzed the 

 egg-cell, but even seemed to affect the structure of the female- 

 parent, a phenomenon called xenia in plants, and often reported, 

 though never confirmed, among animals. But the discovery of 

 this double fertilization removed all mystery from the matter, for 

 the color in the red grains resides wholly in the endosperm, which 

 is a kind of a hybrid between the male and female parents, sharing 

 in the characters of both. 



As our chapter on Protoplasm showed, individuals tend to wear 

 out and die when their protoplasm repeats longtime the same 

 function; but they can live potentially forever if the protoplasm 

 can change periodically its internal arrangement, — can go, so to 

 speak, into the melting pot, and be cast anew. Now there is no 

 more effective remelting than that accompanying sexual reproduc- 

 tion, for a greater change in the constitution of the protoplasm 



